Although applicable to any system in which a pressurized tank is charged with an active ingredient and carrier, in which unauthorized refilling of the tank is to be avoided, the inventive device is specifically useful in the field of pesticide dispensing systems, and is described in that context below.
Pesticide dispensing systems of the type to which the inventive lockout device is directed are described in, for example, U.S. Pat. Nos. 5,020,689 and 5,150,822. In the systems described therein, an active ingredient, such as a pesticide or fumigant, is placed in a sample cylinder, and a pressurized carrier which acts both as a solvent and propellent is subsequently introduced from a carrier source. This solvent/propellent expands in the tank to adopt a liquid phase and a gaseous phase. The liquid phase serves to absorb the active ingredient, while the gaseous phase serves to propel the borne active ingredient out of the apparatus through a dispensing outlet where further expansion takes place and whereby the active ingredient is dispersed in a fog or a mist. Such systems are particularly suitable for the spraying of insecticides where a metered amount of active ingredients is to be dispersed, or for exhausting a total supply of active ingredient.
After exhaustion, the tanks are separated from the dispersing apparatus, and sent for recharging. In the field of pesticides, stringent government control is placed on companies authorized to recharge such tanks and strict precautions must be taken to ensure that unsuitable materials are not placed in the tank. Because of the excellent solvent action of the propellent, the inside of the tanks are extremely clean when returned to the recharging station by the user. In fact, when an empty tank is received, it will contain far less than 1% of the active ingredient with which it was originally charged. Thus, it is not necessary to wash the tanks and, if there were not concerns with contamination from outside sources, the tanks could simply be attached to the refilling apparatus and recharged.
Unfortunately, with the common tank assemblies presently in use, it is not possible to fully verify that no material other than what was originally charged into the tank, has been added. Therefore, due to government regulation, it is necessary to disassemble the head assembly from the tank, and wash it. This procedure is both costly and time consuming.